An adaptive noise canceller based on an improved LMS (least-mean-squares) algorithm has been designed by DSP. The algorithm is introduced and simulated in MATLAB, then realized on the digital signal processor TMS320C 6713. A 50HZ sine wave, used as the referenced input, traces the noise of signal until it is eliminated. Then the expected signal has been obtained. The experiment results indicate that the adaptive noise canceller can remove the 50HZ noise of signal conveniently and effectively, so it has the ideal filter characteristics of narrow-band.